Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductive layers over a semiconductor substrate, and patterning the various material layers using lithography to form circuit components and elements thereon.
One important driver for increasing performance of a semiconductor device is the higher levels of integration of circuits. This is accomplished by miniaturizing or shrinking device sizes on a given chip. Modern integrated circuits are made up of a great amount of active devices such as transistors and capacitors. These devices are initially isolated from each other, but are later interconnected together to form functional circuits. Typical interconnect structures include lateral interconnections, such as metal lines (wirings), and vertical interconnections, such as vias and contacts. Interconnections are increasingly determining the limits of performance and the density of modern integrated circuits. On top of the interconnect structures, bond pads may be formed and exposed on the surface of the respective chip. Electrical connections are made through bond pads to connect the chip to a package substrate or another die.
However, although existing bond pads have been generally adequate for their intended purposes, as device scaling-down continues, they have not been entirely satisfactory in all respects.